On the Interaction of a Wind Turbine Wake with a Conventionally Neutral Atmospheric Boundary Layer

Amy Hodgkin, Georgios Deskos, Sylvain Laizet

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations


In this work, we investigate the dynamics of wind turbine tip-vortex breakdown in a conventionally neutral atmospheric boundary layer (ABL). To this end, high-resolution data are collected from large-eddy simulations of a wind turbine operating within a neutral ABL and studied by means of proper orthogonal decomposition (POD) and Fourier analysis. The high resolution of the generated data in both space and time allows us to gain insight into the tip-vortex breakdown mechanisms by (i) capturing the energy modes of the coherent structures, (ii) studying their contribution to the tip-vortex breakdown through their power spectra functions and mean kinetic energy (MKE) flux, and (iii) analysing the growth rate of each contributing perturbation frequency along tip vortices. Our analysis shows that under a fully turbulent scenario, the growth rate of perturbations along the tip vortices is largest for low wave numbers, i.e. long-wave perturbations. Additionally, the MKE flux reaches its highest value at two diameters downstream of the rotor plane, a behaviour that can be attributed to the coexistence of multiple interacting POD modes, with the streamwise vortex roller mode being the primary contributor to the total MKE flux budget, contributing approximately 24%. Finally, comparisons with a laminar, uniform flow scenario subject to a single-frequency perturbation highlight the differences between the two ambient flow conditions. In the non-turbulent, uniform flow scenario, the growth rate attains its maximum value at a wave number corresponding to the out-of-phase mutual-inductance mechanism, whereas the MKE flux exhibits local minima and maxima along the wake and at different downstream locations depending on the perturbation frequency. Our analyses suggest that the breakdown of the wind turbine tip vortices under a fully turbulent neutral ABL inflow is due to complex interactions across a range of excitation frequencies, in which the mutual-inductance instability may not be the dominant one.

Original languageAmerican English
Article number109165
Number of pages16
JournalInternational Journal of Heat and Fluid Flow
StatePublished - Aug 2023

Bibliographical note

Publisher Copyright:
© 2023 The Author(s)

NREL Publication Number

  • NREL/JA-5000-86115


  • Atmospheric boundary layer
  • Large-eddy simulation
  • Proper orthogonal decomposition
  • Wind turbine tip vortex breakdown


Dive into the research topics of 'On the Interaction of a Wind Turbine Wake with a Conventionally Neutral Atmospheric Boundary Layer'. Together they form a unique fingerprint.

Cite this